Grotius Establishes the Concept of International Law
Hugo Grotius, often referred to as the father of international law, significantly shaped legal thought in the early 17th century with his landmark work, "On the Law of War and Peace." Born in 1583 in Delft, Holland, Grotius was a prodigious talent, achieving notable academic and professional milestones at a young age. His writings introduced key concepts such as the just war theory, arguing that war could be justified under certain circumstances, particularly when responding to injury. This work emerged during a tumultuous period marked by the Thirty Years' War, providing a framework for regulating relations between emerging sovereign states.
Grotius's treatise is grounded in the concept of the ius gentium, or law of nations, which he believed should govern interactions among communities, irrespective of their political organization. Through a detailed examination of rights and humanitarian principles, Grotius emphasized the importance of legal obligations and the enforcement of laws, even in times of conflict. His ideas drew upon a rich tapestry of classical thought and were aimed at promoting moderation and justice in warfare. The enduring influence of Grotius is reflected in the continued relevance of his principles in contemporary discussions of international law and conflict resolution.
Grotius Establishes the Concept of International Law
Locale Paris, France
Date 1625
Grotius’s major work, On the Law of War and Peace, is widely considered the first definitive text on international law. It provides a systematic description and prescription of the behavior of national communities, which, he argues, have legal rights as well as duties. The work anticipated the advent of the modern state system after 1648.
Key Figures
Hugo Grotius (Huig de Groot; 1583-1645), Dutch jurist, theologian, statesman, diplomat, poet, and author of works on law and jurisprudence, theology, and cultural historyMaurice of Nassau (1567-1625), Dutch stadtholder, or chief executive, and commander-in-chief who employed Grotius as legal counsel in 1604 but had him arrested and brought to trial for sedition in 1618-1619Louis XIII (1601-1643), king of France, r. 1610-1643, who granted Grotius safety and a modest stipend when Grotius fled to Paris in 1621Christina (1626-1689), queen of Sweden, r. 1644-1654, who dismissed Grotius from the Swedish diplomatic service in 1644Maria van Reigersbergh de Groot (1589-1653), wife of Hugo Grotius, who helped Grotius escape to France
Summary of Event
Known as the father of international law, Huig de Groot, who used the Latinized version of his name, Hugo Grotius, was born to an old and distinguished Dutch family in Delft, Holland, in 1583. Grotius was a child prodigy who wrote Greek and Latin poetry, matriculated at the University of Leiden at age eleven, received a doctor of laws degree from the University of Orléans (France) at fifteen, and was admitted to the Dutch bar at sixteen.
Grotius became his country’s official historiographer at eighteen and legal counsel to the Dutch ruler, Prince Maurice of Nassau , at twenty-one. He continued advancing in public and diplomatic posts until 1618 when, becoming involved in a political-religious controversy, Grotius, along with other senior officials, was arrested and sentenced to life imprisonment in Loevestein fortress for treason.

Yet in March of 1621, with the help of his wife, Maria van Reigersbergh, and his maid, Grotius managed to escape from the castle where he was held and to flee to France where, at first, he was well received and got the moral and financial support of King Louis XIII . Beginning in 1622, in a Paris suburb, he began drafting his magnum opus in Latin, De jure belli ac pacis libri tres (1625) translated into English as On the Law of War and Peace (1654). Other well-known works by Grotius in law and jurisprudence include Apologeticus eorum qui Hollandiae Westfrisiaeque et vicinis quibusdam natioibus ex legibus praefuerunt (defense of the lawful government of Holland and West Friesland, together with some neighboring provinces, as it was before the change occurring in 1618), Inleidinge tot de Hollandsche Rechts-geleerdheyd(pb. 1631; Introduction to Dutch Jurisprudence, 1845), De jure praede commentarius (wr. c. 1604-1606; Commentary on the Law of Prize and Booty , 1950), and Mare liberum (1609; The Freedom of the Seas , 1916). Yet his great versatility is evidenced by his publications in other fields as well.
In 1631, Grotius returned to Holland in defiance of his outlaw status but was forced to flee the following year. He at first took refuge in Germany but then moved to Stockholm where, in 1634, he was offered the Swedish ambassadorship to Paris. He helped to negotiate the Franco-Swedish Treaty of 1635 and others but was relieved of his post by the newly ascended Queen Christina of Sweden in 1644. In 1645, Grotius returned to Stockholm but declined the alternative employment offered him in the Swedish service. On his way to Rostock, Germany, he was shipwrecked in the Baltic Sea and died of exhaustion two days later on August 28, 1645. Grotius was subsequently buried in his home town of Delft.
On the Law of War and Peace, a work in international law, is an expansion of Grotius’s ideas outlined in his earlier work. The book is premised on his idea of civil society governed by the ius gentium, the law of nations. The latter in turn is based on common natural law, fundamental to human nature and discoverable by human reason. This law of nations should dictate relations between communities not yet organized as units of political society as well as between national states since no community can exist without law. The theme, heralded by a long line of thinkers from classical times on, is developed in Grotius’s three-volume treatise, the original 1625 edition running to 786 pages. It falls into two major parts: first, the legal obligations of human societies, including those with sovereign power; and second, how to enforce such obligations and punish violations of law—vital features of Grotius’s message. This message declares that communities have legal rights and duties, and that war is a law-enforcement procedure similar to judicial remedies.
Book 1 (five chapters) of On the Law of War and Peace inquires whether war is ever justified. Grotius’s answer, contradicting pacifist opinion and many Christian theologians, is that it is justified when an injury of some sort is the cause. Book 2 (twenty-six chapters) holds that there can therefore be as many just causes of war as there are types of injuries. Grotius also admonishes against going to war too hastily, even for just cause, and recommends conferences and arbitrations, even contests among the leaders themselves, as preferred alternative methods of settling disputes. To reach his conclusions, Grotius reviewed the entire gamut of substantive rights under municipal law, for “there is a common law among nations, which is valid alike for war and in war.” Book 3 (twenty-five chapters) deals with the actual conduct of war, that is, the humanitarian rules that belligerents must observe during hostilities. Grotius’s counsels of moderation flow from his basic belief in rights common to all humans, which were often ignored in the barbarities of the Thirty Years’ War.
The work abounds in references to the Bible, ancient orators and statesmen, classical historians, philosophers, even poets, but avoids contemporaneous controversial matters. Many of the references are to establish historical authenticity or clarity but some are for adornment. Whatever the purpose, the influence of Greek, Roman, and medieval thinking on Grotius’s formulation of international law is unmistakable.
Significance
The elaboration of “rules” in On the Law of War and Peace by Grotius could not have come at a better time. For the bloody Thirty Years’ War leading to the Peace of Westphalia in 1648 transformed numerous petty principalities into separate sovereign states. Grotius’s great work provided a body of laws to regulate their relations.
In addition to the timing of his writing, Grotius’s persona and his scholarly reputation contributed to the success of his treatise. Another factor in this success was his Dutch heritage. Holland was one of the dominant countries of Europe that had spearheaded the idea of the nation-state. It is not surprising, then, that since its publication, the book crafted by the one dubbed “the wonder of Holland” and “the jurisconsult of humankind” has gone through about one hundred editions and numerous translations.
Bibliography
Bull, Hedley, Benedict Kingsbury, and Adam Roberts, eds. Hugo Grotius and International Relations. Oxford, England: Clarendon Press, 1992. A collection of essays based on a series of commemorative lectures at Oxford University in 1983. Several of the contributions touch on Grotius’s seminal work.
Dumbauld, Edward. The Life and Legal Writings of Hugo Grotius. Norman: University of Oklahoma Press, 1969. This brief book by an American judge includes an excellent critical essay on Grotius’s major text.
Edwards, Charles S. Hugo Grotius, the Miracle of Holland: A Study in Political and Legal Thought. Chicago: Nelson-Hall, 1981. This book examines Grotius’s works on the basis of his most eminent concepts—the law of nature, the law of nations, and the law of war. Includes extensive notes and a bibliography.
Gellinek, Christian. Hugo Grotius. Boston: Twayne, 1983. The author, a corresponding member of the journal Grotiana published in the Netherlands, includes a critical evaluation of Grotius’s major work in chapter 5, “Legal Treatises.” Also contains an excellent and detailed tabulation of the body of Grotius’s writings.
Grotius, Hugo. On the Law of War and Peace. Translated by Francis W. Kelsey, et al. New York: Bobbs-Merrill, 1925. Based on the 1646 edition of the Latin original, the last edition to be revised by Grotius, this 1925 translation is the translation used most frequently by international lawyers and scholars and is widely accessible.
Haakonssen, Knud, ed. Grotius, Pufendorf, and Modern Natural Law. Brookfield, Vt.: Ashgate, 1999. This work discusses various aspects of the philosophies of Grotius and his contemporary Samuel von Pufendorf, including their ideas on the modern state.
Knight, William S. M. The Life and Work of Hugo Grotius. 1925. Reprint. Dobbs Ferry, N.Y.: Oceana, 1962. An authoritative work by an Oxford scholar and lawyer. Despite the many intervening years, Knight’s work is one of the few biographies on Grotius written in English.
Onuma, Yasuaki, ed. A Normative Approach to War: Peace, War, and Justice in Hugo Grotius. Oxford, England: Clarendon Press, 1993. The revised and translated version of a book by six Japanese professors of international law that examines various aspects of Grotius’s output. The translated and indexed list of key Latin terms used by Grotius adds to the book’s significance.
Tuck, Richard. The Rights of War and Peace: Political Thought and the International Order from Grotius to Kant. New York: Oxford University Press, 1999. Tuck examines the work of numerous philosophers who laid the foundation for modern theories of international law. He focuses on seventeenth and eighteenth century thinkers, including Grotius, Thomas Hobbes, and John Locke.
Vollenhoven, Cornelis van. The Framework of Grotius’ Book “De Iure Belli ac Pacis,” 1625. Amsterdam: Noord-Hollandsche, 1931. A perceptive and detailed analysis of On the Law of War and Peace by perhaps the foremost modern Dutch expert on Grotius.